Encoder-decoder system

ABSTRACT

In combination with a plurality of encoders each of which can generate a different pulse duration coded (PDC) signal which uniquely identifies it: a converter responsive to incoming PDC signals supplied thereto from the encoders to derive therefrom corresponding pulse position coded (PPC) signals which also uniquely identify the corresponding encoders; first means to supply said PDC signals from said encoders to said converter; a like plurality of decoders each of which is adapted to respond to the presence of the PPC signal which uniquely identifies the encoder corresponding to it to produce an output signal, each decoder being non-responsive in the absence of the unique identifying signal; and second means to supply said PPC signals from said converter to all of said decoders in parallel.

Codina [111 3,748,388 July 24, 1973 1 ENCODER-DECODER SYSTEM [75]Inventor: Jorge G. Codina, Hartsdale, NY.

[73] Assignee: Comard Controls Inc., New York 221 Filed: on. 19,1971

[211 Appl. No.: 190,595

[52] US. Cl 179/5 R, l79/2.5 R, 179/15 BA [51] Int. Cl. ll04m 11/04 [58]Field of Search 179/15 BA, 2 A, 5 R, 179/2.5 R; 325/55; 340/223, 275;307/234, 265, 266

[56] References Cited UNITED STATES PATENTS 3,239,761 3/1966 Goode179/15 BA 3,482,049 12/1969 Kobayashi.. 179/15 BA 3,422,226 1/1969 Acs179/15 BA 3,160,711 12/1964 Schroeder 325/55 3,387,091 6/1968 Deiker179/5 R 3,452,345 6/1969 Kinsey 179/5 R OTHER PUBLICATIONS IEEESpectrum, Multiple-Access Discrete-Address Communication Systems,"August 1967, pp. 87-94.

Primary Examinerl(athleen H. Claffy Assistant ExaminerDavid L. StewartAttorney-Theodore Jay, Jr.

[57] ABSTRACT In combination with a plurality of encoders each of whichcan generate adifferent pulse duration coded (PDC) signal which uniquelyidentifies it: a converter responsive to incoming PDC signals suppliedthereto from the encoders to derive therefrom corresponding pulseposition coded (PPC) signals which also uniquely identify thecorresponding encoders; first means to supply said PDC signals from saidencoders to said converter; a like plurality of decoders each of whichis adapted to respond to the presence of the PPC signal which uniquelyidentifies the encoder corresponding to it to produce an output signal,each decoder being nonresponsive in the absence of the uniqueidentifying signal; and second means to supply said PPC signals fromsaid converter to all of said decoders in parallel.

6 Claims, 4 Drawing Figures DECODER e W 2 ENCODER---'- PPMPDM 0CONVERTER ELAY GATE "'1 l"" COINCIDEN T I /4 l6 L 2ND 2ND IL DELAY GATECO/NCIDENT -L.l

SIGNAL our To DISPLAY AND CONTROL PAIENIEUJULZMQH Eff/48,388

SHEET 1 BF 2 TRANSM/TTED SIGNAL RECEIVED SIGNAL AFTER DIFFERENTIATION AB C CONVERTER OUTPUT CO/NC/DENT our A-B (2N0) INVEN TOR.

JORGE G. COD/NA ATTORNEY Pmmmm ENCODER SHEEI 2 [IF 2 DECODER /o //2PPM-PDM 1r"- COINCIDENT l4 /6 L 2ND 2ND J1 DELAY GATE T COlNC/DENT 'LT'2ND C F/G 2 SIGNAL our TO DISPLAY AND CON TROL INVEN TOR.

JORGE G. C OD/NA ATTORNEY ENCODER-DECODER SYSTEM SUMMARY OF THEINVENTION My invention is directed toward a system employing a pluralityof encoders, a like plurality of decoders and a code converter. Eachencoder produces a corresponding encoded signal of the pulse durationcoded (PDC) type; the converter converts each PDC signal to acorresponding pulse position coded (PPM) signal; and each decoderresponds only to the particular PPC signal which is associated with thecorresponding encoder.

Typically, each encoder can be associated with a corresponding remotedoor to produce its encoded signal when the door is opened. Each decoderis not only associated with a corresponding encoder, but also acorresponding display device in a common display panel whereby when alldecoders, which are in parallel, receive all PPC signals, each decoderresponds only to the presence of the signal of its corresponding encoderto actuate the appropraite display device to inform a user that a doorhas been opened. This enables one watchman to inspect the condition,open or closed, of a plurality of remotely disposed doorssimultaneously.

The converter simplifies the number of components, as well as theexpense of same as required in the system by converting or transformingPDC to PPC signals prior to supplying same to the decoders. A verysimple decoder can be used with PPC signals whereas a complex andexpensive decoder is required when PDC signals are used Typically, theencoded signals can be supplied to the converter via existing powerlines, although additional cable can be used if desired.

BRIEF DESCRIPTION OF THE DRAWINGS DETAILED DESCRIPTION OF PREFERREDEMBODIMENTS In my invention, a plurality of encoders can be used whereineach encoder is located at a different one of a like plurality ofremotely disposed doors. Each encoder will release a paraticular encodedsignal uniquely identifying it when the corresponding door is opened.All encoded signals can take the form of pulse duration coded (PDC)signals.

These signals can be fed over existing power lines or other cable to theinput of a converter wherein the PDC signals are converted intocorresponding pulse position coded (PPC) signals.

The PPC signals are supplied to the paralleled inputs of a likeplurality of decoders. For each encoded PPC signal, there is one andonly one corresponding decoder which will respond to its presence toproduce an output signal. In the absence of its corresponding PPCsignal, the corresponding encoder will be quiescent.

The outputs of the decoders can be coupled to corresponding lampcircuits in a display device having a like plurality of lamps. Each lampcan have a different number corresponding to a different door and willbe lit to indicate that its corresponding door has bwen opened when andonly when the corresponding encoder has produced a PDC signal convertedto a PPC signal by the converter and supplied to the correspondingdecoder to produce the output signal supplied to the proper lampcircuit.

As shown in FIGS. 1 and 2, encoder can produce a PDC in the form of asignal having first and second pulse components, the second componentimmediately following the first component in time sequence. Thecomponents are pulses having like plurality and have independentlycontrollable durations. These durations constitute a code. One encoderof this type is shown and described in my copending application, Ser.No. 185,971 filed Oct. 4, 1971, entitled Encoder. One typical signal isshown at l in FIG. 1.

More particularly, in the Encoder application, a first single shotmultivibrator produces a first unidirectional output pulse of givenpolarity, the pulse duration being determined by a first time constantnetwork of the first multivibrator. A second single shot multivibratoris coupled to the first multivibrator and is responsive to the trailingedge of the first pulse to produce a second unidirectional pulse of likepolarity. The duration of the second pulse is determined by another timeconstant network of the second multivibrator. Means coupled to theoutputs of both multivibrators produces a composite or temporalsummation of both pulses. The first and second pulses form the first andsecond components and the summation is the desired signal.

The converter 10 receives PDC signals from all encoders 80 along a powerline 82 or other cable. Each such signal is differentiated in theconverter to produce a first spike of given polarity, then a pair ofspikes, the first of which has reversed polarity, the second of whichhas the given polarity, then an additional spike of reversed polarity asshown at 2 in FIG. 1. The converter then produces a train of threespaced pulses A, B and C of like duration. The time separation betweenpulses A and B is proportional to the time interval between the firstspike and the first spike in the pair and thus is proportional to theduration of the first component in hte original PDC signal. The timeseparation between the pulses B and C is proportional to the timeinterval between the first spike in the pair and the additional spikeand thus is proportional to the duration of the second component in theoriginal PDC signal. The resultant PPC signal is shown at 3 in FIG. 1.One converter of this type is shown and described in my copendingapplication, Ser. No. 185,969, filed Oct. 4, 1971 entitled CodeConverter.

More particularly, in the Code Converter application, apparatus respondsto an incoming signal which can be the output signal produced by theEncoder apparatus previously described. The output signal isdifferentiated to produce a first unidirectional spike of firstpolarity, then a pair of spikes, the first of which has reversedpolarity, the second of which has the polarity, then an additional spikeof reversed polarity. The period between the first spike and the firstspike in the pair is equal to the duration of the first pulse componentin the putput signal. The period between the first spike in the pair andthe additional spike is equal to the duration of the second pulsecomponent.

A normally non conductive single shot multivibrator, when triggered intoconduction, produces an output pulse of fixed duration which is lessthan the duration of either pulse component. Means responsible to thedifferentiated signal and thus responsive to the various strikes passesthe second spike in the pair to the multivibrator in such manner as tohave no effect on the conduction thereof and passes the first spike, thefirst spike in the pair and the additional spike to cause each of thesethree passed spikes to trigger the multivibrator into conduction wherebythe desired train of three pulses is produced.

Each decoder constitutes delay circuits 11 and 14, gates 12 and 16 andcoincidence circuits 13 and 15. In the decoder, the PPC signals passsuccessively there through without delay as well as with specifieddelays. The values of the delays vary from decoder to decoder incorrespondence with the corresponding encoded signals. When a decoderreceives its designated encoded signal, it generates an output pulse.Otherwise the decoder is quiescent.

FIG. 2 shows a decoder receiving its designated signal and FIG. 1 showsthe appropriate wave forms. Basically, pulse A after being delayed incircuit 11 and being inverted in gate 12 arrives at circuit 13 in timecoincidence with undelayed pulse B whereby circuit 13 produced a firstpulse. This first pulse after being delayed in circuit 14 and beinginverted in gate 16 arrives at circuit in time coincidence withundelayed pulse C. Circuit 15 then produces the desired output pulse.All other decoders have one or two different delay periods and thus willnot respond to the particular encoded signal shown. In this way eachencoder is keyed to its corresponding decoder and to no other.

Referring now to FIG. 3, the delay circuit comprises a one shotmultivibrator employing transistors 60 and 61 which is triggered by theleading edge of the first of the two pulses with which it is concerned.The duration of the pulse yielded by the mublivibrator is determined bythe time constant network employing capacitor 59 and resistor 54 and isset as desired.

FIG. 4 shows a typical coincidence circuit with the output from a gatepassing through diode 65 and resistor 63 to the base of transistor 67and the pulse input (shown as B in the Figure) passing through diode 66to resistor 63. The junction of these diodes and resistor 63 isconnected via resistor 62 to a point of positive potential. This pointis connected to the collector of transistor 67. The emitter is groundedthrough resistor 64. Consequently, the desired output signal is onlyproduced upon coincidence of the gate signal and the pulse as shown.

While I have described my invention with particular reference to thedrawings and to specific embodiments, my protection is to be limitedonly by the terms of the claims that follow.

I claim:

1. In combination with a plurality of encoders, each of which generates,when activated, a different pulseduration coded (PDC) signal whichuniquely identifies the said each encoder;

A converter responsive to incoming PDC signals supplied thereto fromsaid encoders to derive therefrom corresponding pulse position coded(PPC) signals which also uniquely identify the corresponding encoders;

first means to supply said PDC signals from said encoders to saidconverter;

a like plurality of decoders each of which is responsive to the presenceof the .PPC signal which uniquely identifies the encoder correspondingto said each decoder to produce an output signal, each decoder beingnon-responsive in the absence of said uniquely identifying signal; and

second means to supply said PPC signals from said converter to all ofsaid decoders in parallel.

2. The combination of claim 1 wherein said first means includes powerlines.

3. The combination of claim 2 wherein the PPC signals each employ threespaced pulses of like polarity and width.

4. The combination of claim 3 wherein each decoder contains a firstdelay circuit to delay the first pulse until the second pulse arrives intime coincidence with the delayed first pulse; a firstcoincidencecircuit to produce an output pulse when said secondpulse-delayed first pulse coincidence occurs; a second delay circuit todelay the output pulse until the third pulse arrives in time coincidencewith the delayed output pulse; and a second coincidence circuit toproduce the desired output signal when said delayed output-third pulsecoincidence occurs.

5. The combination of claim 2 wherein each decoder is provided withmeans for passing through PPC signals without delay as well as means forpassing through PPC signals with specified delays, the values of thedelays varying from decoder to decoder in correspondence with thecorresponding encoded signals.

6. The combination of claim 5 wherein the PDC signals are eachconstituted by first and second pulses disposed in immediate timesequences, said pulses having like polarity and variable widths.

1. In combination with a plurality of encoders, each of which generates,when activated, a different pulse-duration coded (PDC) signal whichuniquely identifies the said each encoder; A converter responsive toincoming PDC signals supplied thereto from said encoders to derivetherefrom corresponding pulse position coded (PPC) signals which alsouniquely identify the corresponding encoders; first means to supply saidPDC signals from said encoders to said converter; a like plurality ofdecoders each of which is responsive to the presence of the PPC signalwhich uniquely identifies the encoder corresponding to said each decoderto produce an output signal, each decoder being non-responsive in theabsence of said uniquely identifying signal; and second means to supplysaid PPC signals from said converter to all of said decoders inparallel.
 2. The combination of claim 1 wherein said first meansincludes power lines.
 3. The combination of claim 2 wherein the PPCsignals each employ three spaced pulses of like polarity and width. 4.The combination of claim 3 wherein each decoder contains a first delaycircuit to delay the first pulse until the second pulse arrives in timecoincidence with the delayed first pulse; a first coincidence circuit toproduce an output pulse when said second pulse-delayed first pulsecoincidence occurs; a second delay circuit to delay the output pulseuntil the third pulse arrives in time coincidence with the delayedoutput pulse; and a second coincidence circuit to produce the desiredoutput signal when said delayed output-third pulse coincidence occurs.5. The combination of claim 2 wherein each decoder is provided withmeans for passing through PPC signals without delay as well as means forpassing through PPC signals with specified delays, the values of thedelays varying from decoder to decoder in correspondence with thecorresponding encoded signals.
 6. The combination of claim 5 wherein thePDC signals are each constituted by first and second pulses disposed inimmediate time sequences, said pulses having like polarity and variablewidths.